java如何实现群聊,用Java控制台实现简单的群聊天室

Java实现群聊的方法有很多种，其中一种比较简单的方法是使用Java Socket编程实现。

以下是一个简单的Java控制台群聊天室的代码：

1. 服务端代码

import java.io.*;
import java.net.*;
import java.util.*;

public class Server {
    private static List<Socket> sockets = new ArrayList<>();

    public static void main(String[] args) {
        try {
            ServerSocket server = new ServerSocket(8888);
            System.out.println("服务器已启动，等待客户端连接...");
            while (true) {
                Socket socket = server.accept();
                sockets.add(socket);
                System.out.println("客户端已连接，当前连接数：" + sockets.size());
                new ServerThread(socket).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static class ServerThread extends Thread {
        private Socket socket;
        private BufferedReader reader;

        public ServerThread(Socket socket) {
            this.socket = socket;
            try {
                reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void run() {
            String line;
            try {
                while ((line = reader.readLine()) != null) {
                    System.out.println("客户端消息：" + line);
                    for (Socket socket : sockets) {
                        if (socket != this.socket) {
                            PrintWriter writer = new PrintWriter(socket.getOutputStream());
                            writer.println(line);
                            writer.flush();
                        }
                    }
                }
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    socket.close();
                    sockets.remove(socket);
                    System.out.println("客户端已断开连接，当前连接数：" + sockets.size());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

2. 客户端代码

import java.io.*;
import java.net.*;

public class Client {
    public static void main(String[] args) {
        try {
            Socket socket = new Socket("127.0.0.1", 8888);
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            PrintWriter writer = new PrintWriter(socket.getOutputStream());
            new ClientThread(socket).start();
            String line;
            while ((line = reader.readLine()) != null) {
                writer.println(line);
                writer.flush();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static class ClientThread extends Thread {
        private Socket socket;
        private BufferedReader reader;

        public ClientThread(Socket socket) {
            this.socket = socket;
            try {
                reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void run() {
            String line;
            try {
                while ((line = reader.readLine()) != null) {
                    System.out.println("收到消息：" + line);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

以上代码实现了一个简单的Java控制台群聊天室，服务端启动后等待客户端连接，客户端连接后可以发送消息，服务端接收到消息后将其转发给所有连接的客户端。